Will fit 450 Bushmaster & .458 caliber barrel with 11/16" x 24 Thread Pattern.
Also work to shim the M-14 M1A gas system snug to the barrel.
Please check fitment before ordering.
TACSHIM will be an ideal and new solution for you, whether you've tried the thread locker/crush washer/peel washer or not.
TACSHIM offers a far greater degree of precision than that of any crush washer or peel washer, also let you being faster and less labor intensive to install correctly.
Tips:
TACSHIM shims can be used alone or in different combinations.
This is just a game of trial and error to get your desired thickness.